JPH02158812A - Pressure reducing valve - Google Patents

Abstract

PURPOSE:To prevent a chattering phenomenon by providing a piston with a passage to connect a piston chamber of the upper space of the piston and a secondary side pressure area of lower space, and arranging a valve energized by a energizing spring in the middle of said passage. CONSTITUTION:If chattering occurs, the pressure of the piston chamber 20a fluctuates remarkably by the rapid opening and the rapid closing of a pilot valve. The pressure raised high instantaneously overcomes the energizing force of the energizing spring 80, and opens a valve body 78, and releases fluid in the piston chamber 20a to the secondary side pressure area 16. Accordingly, the pressure raised high instantaneously in the piston chamber 20a is absorbed, and the piston 20 never operates violently, but descends smoothly, and a main valve opens slowly as well, and the response of the piston to the sudden opening of the pilot valve is delayed. Thus, secondary pressure is never raised suddenly, and stable feedback pressure is transmitted to a diaphragm, the pilot valve, etc., and the chattering never occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a pressure reducing valve that is attached to a piping system for steam, compressed air, etc. to maintain fluid pressure on the secondary side at a constant set pressure.

<Prior Art> A conventional pressure reducing valve is as shown in FIG. 2, and consists of a pressure reducing valve section 1, a steam/water separator section 2, and a drain valve section 3.

The main body 10 has an entrance 12. Benro] 4. An outlet 16 is formed.

The inlet is connected to a high-pressure fluid source on the primary side, and the outlet is connected to a low-pressure region on the secondary side. The main valve 18 is disposed at the inlet side end of the valve port 14 and is elastically biased by a main valve spring 19.

The piston 20 is slidably disposed within the cylinder 22, and the piston rod 20b is brought into contact with the central protrusion 18a of the main valve 18 through the valve port 14. The lower surface of the piston 20 and the piston rod 20b are connected by a substantially hemispherical surface, and an orifice 20G is opened that communicates the upper space and the lower space. A pilot valve 26 is disposed in a primary pressure passage 24 that communicates the inlet 12 with the space above the piston 20, that is, the piston chamber 20a. The diaphragm 28 is mounted with its outer peripheral edge sandwiched between the flanges 30,32. The space below the diaphragm 28 communicates with the outlet 16 through a secondary pressure detection passage 34 . The head end surface of the valve stem 36 of the pilot valve 26 abuts against the central lower surface of the diaphragm 28 . Also, the pilot valve 26 is connected to the pilot spring 2? − is biased in the valve closing direction.

A pressure setting coil spring 40 is brought into contact with the upper surface of the diaphragm 28 via a spring seat 38. The adjustment screw 44 is screwed and attached to the spring case 66.

By turning the adjustment screw 44 left and right, the elastic force of the pressure setting spring 40 that pushes down the diaphragm 28 changes.

Using the elastic force of the pressure setting spring 40 as a reference value, the diaphragm 28 curves in response to the secondary pressure acting on its lower surface, displacing the valve rod 36 and opening and closing the pilot valve 26. As a result, the primary side fluid pressure increases to the piston chamber 20.
a, the piston 20 is driven to displace the main valve 18, and the fluid at the inlet 12 flows through the valve port 14 to the outlet 16. This automatically operates so that the valve port 14 opens when the fluid pressure on the secondary side decreases and closes when it increases.

A cylindrical partition member 46 is attached below the valve port 14,
An annular space 48 is formed between the main body 10 surrounding the annular space 48, and the upper part of the annular space 48 is passed through a cone-shaped screen 50 to the inlet 12.
The lower part communicates with the upper part of the drain valve chamber 52. Further, the upper part of the drain valve chamber 52 communicates with the valve port 14 through the central opening of the partition member 46 . A swirl vane 54 made of an inclined wall is arranged in the annular space 48.

Therefore, when the valve port 14 opens and the fluid in the inlet 12 passes through the annular space 48, its direction is bent by the swirl vanes 54 and the fluid is swirled. The liquid is shaken out to the outside, hits the surrounding inner wall of the main body, and flows down into the drain valve chamber 52, while the light gas swirls in the center and flows from the central opening of the partition member 46 to the valve port 1.
4, through which it flows away to exit 16.

A drain valve port 58 communicating with the drain port 56 is formed at the bottom of the drain valve chamber 52 . Covered with a float cover 62, a spherical valve float 60 is movably accommodated. A ventilation hole 64 is opened in the upper part of the float cover 62.

Therefore, the valve float 60 floats up and down with the water level in the drain valve chamber 52 to open and close the drain valve port 58, and automatically removes water accumulated in the drain valve chamber 52.

<Problems to be Solved by the Invention> In all existing pressure reducing valves, including the conventional pressure reducing valve having the above-mentioned configuration, there is a chattering phenomenon that causes significant imaging and noise, which cannot be resolved. This means that even if the pressure is set at an appropriate flow rate, it will operate normally.
It occurs when the load on the secondary side decreases and the flow rate decreases, or it also occurs when the set pressure (secondary pressure) is smaller than the negative pressure, that is, when the pressure reduction ratio is large.

The pressure reduction ratio is, for example, when the primary pressure of 1 ONff/cm is reduced to less than the secondary pressure of 2 Ky/c/, and movable parts such as the main valve 18 and the piston 20 vibrate, causing a chattering phenomenon. This is because when the secondary pressure decreases and the pressure change is transmitted through the secondary pressure detection passage 34, and the pilot valve 26 opens, the valve opens by more than the pressure drop and then returns to the valve closing direction. By repeating this (a state of commotion is exhibited, a rapid pressure fluctuation occurs in the piston chamber 208 in the space above the piston 20, and the movement of the piston 20 is simultaneously transmitted to the main valve 18 that is in contact with the lower part of the piston 20).
One cause is thought to be the vibration of the pilot valve 26, in which the main valve 18 also exhibits a vibrating state. As the main valve 18 opens and closes, the secondary pressure pulsates, and this sensing acts again on the lower surface of the diaphragm via the secondary pressure detection passage 34, causing the pilot valve 26 to open and close.

This process is performed at an accelerated rate, resulting in a large imaging state.

In addition, the vibration is caused by the sudden opening of the main valve 18, which causes a jet of steam heading toward the secondary side to act on the lower surface of the piston 20, rapidly pushing up the piston 20 and colliding with its upper wall, resulting in the rise of the piston 20. This is considered to be because the main valve 18 cannot follow the piston 20 and collides with the piston 20 when it descends again. Re-contact is shocking, and such operation of the main valve 18 and piston 20 poses problems such as damage to the shaft portion 20b of the piston 20 and damage to the valve seat of the main valve 18. Damage to these members may make it impossible to set the secondary pressure or shorten the life of the pressure reducing valve.

Therefore, the technical object of the present invention is to provide a pressure reducing valve that does not cause the chattering phenomenon.

<Technical means for solving the problems> The technical means of the present invention taken to solve the above problems are as follows:
A main valve is provided between the inlet connected to the primary side and the outlet connected to the secondary side, and the pilot valve is opened when the pressure response part detects that the secondary side pressure has fallen below the set pressure. In a pressure reducing valve configured to open the main valve so that the primary side pressure is introduced into the piston chamber by moving the piston forward, and the secondary side pressure is set to the set pressure by the movement of the piston, the piston has a space above the piston chamber. A passage is opened that communicates with the secondary side pressure area which is the lower space, a valve seat is formed on the secondary side pressure area side in the middle of the passage, and a biasing spring is applied to the valve body so as to come into contact with the valve seat. It is placed under pressure.

Effects> During normal operation without chattering, the pressure in the piston chamber is stable and only changes slowly during slight pressure fluctuations. At that time, the closing force of the valve body provided in the passage connecting the piston up and down is greater than the pressure in the piston chamber, so the fluid in the piston chamber operates normally without flowing out to the secondary pressure area. .

However, if jitter occurs, the pressure in the piston chamber fluctuates significantly due to the sudden opening and closing of the pilot valve, as described above. The instantaneously increased pressure overcomes the biasing force of the biasing spring and opens the valve body, allowing the fluid in the piston chamber to escape to the secondary pressure area. As a result, the instantaneous rise in pressure in the piston chamber is absorbed, and the piston descends smoothly without sudden movement. As a result, the main valve does not open suddenly, but opens slowly after a short delay. That is, by delaying the response of the piston to the sudden opening of the pilot valve, the secondary pressure does not rise rapidly, stable feedback pressure is transmitted to the diaphragm, pilot valve, etc., and chattering does not occur.

<Example> An example showing a specific example of the above technical means will be described. (
(See FIG. 1) This embodiment is an improved piston part of a conventional pressure reducing valve, and parts corresponding to those in FIG. 2 are given the same reference numerals, and a detailed explanation of the pressure reducing valve will be omitted.

Although not shown and explained in detail in FIG. 2, an annular groove is provided on the side surface of the piston 20, piston rings 25a, b made of fluororesin are arranged, and biasing springs 29a, b are applied from the inside.
It is stretched outward and slidably accommodated in the cylinder 22. Then, an orifice 20G that communicates the space above and below the piston 20 is opened.

A valve that has a passage 70 that communicates between the piston chamber 20a, which is the upper space of the piston 20, and the secondary side pressure region 16a, which is the lower space, in the central axis of the piston, and has the piston valve lower 2 on the piston chamber side of the passage 70. The seat member 74 is screwed together with a gasket 76 keeping the two airtight. The valve seat member 74 has a cylindrical shape, and a piston valve body 78 is arranged so as to close the piston valve lower 2 from the inside thereof, and is biased by a biasing spring 80 from the rear thereof.

The action is as follows. piston 20 and cylinder 2
2, piston rings 25a and 25b made of fluororesin are arranged between the piston rings 25a and 25b to improve sliding performance and airtightness, and are stretched from the inside to the outside by biasing springs 29a and 29b. And the piston
By releasing a certain amount of pressure (fluid) 208 from the orifice 20G, the pressure balance between the upper and lower sides of the piston is maintained.

During stable operation without chattering, the secondary pressure, diaphragm 28, pilot valve 26, piston 20, and main valve 18 fluctuate in a slow cycle, so the piston 20 is also slowly displaced by the main valve 18. convey.

At this time, since the pressure in the piston chamber 20a is stable, the pressure is smaller than the force with which the biasing spring 80 presses the piston valve body 78 against the piston valve lower 2. Therefore, the piston valve lower 2 does not open and the fluid in the piston chamber 20a flows through the orifice 2.
A certain amount flows out from 0c.

However, if jitter occurs, the pressure in the piston chamber 20a fluctuates significantly due to the sudden opening and closing of the pilot valve 26, as described above. The momentarily high pressure is applied to the biasing spring 8.
The piston valve element 78 is opened by overcoming the urging force of 0, and the fluid in the piston chamber 2Qa (7) is released to the secondary pressure vi16a. As a result, the instantaneous rise in pressure in the piston chamber 20a is absorbed, and the piston 20 descends smoothly without sudden movement.

As a result, the main valve 18 does not open suddenly, but opens slowly with a slight delay. That is, by delaying the response of the piston 20 to the sudden opening of the pilot valve 26, the main valve 18 is not suddenly opened, and the secondary pressure is not suddenly increased accordingly, and the diaphragm 28, the pilot valve 26, etc. A stable feedback pressure is transmitted and chattering does not occur.

Here, the spring constant of the biasing spring 80 can be easily determined by actually measuring the pressure in the piston chamber 20a when chattering occurs.

<Effects of the Invention> As described above, according to the present application, chattering is eliminated, so vibrations are eliminated and each member is not damaged, and the pressure reducing valve can continue to maintain the set pressure in a stable state.

Furthermore, by eliminating chattering, it becomes possible to set pressures in a low pressure range, which could not be set conventionally, and the range of use as a pressure reducing valve becomes wider.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a piston according to an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional pressure reducing valve. 10: Main body 12: Inlet 16: Outlet 20: Piston 26: Pilot valve 28: Diaphragm 70: Passage
72: Piston valve lower 4: Valve seat member 78
: Piston valve body 80: Biasing spring

Claims (1)

[Claims] 1. A main valve is provided between the inlet connected to the primary side and the outlet connected to the secondary side, and the pressure-response part detects that the secondary side pressure has fallen below the set pressure and activates the pilot valve. In a pressure reducing valve configured to open the main valve so that the primary pressure is introduced into the piston chamber by opening the main valve and the secondary pressure is set to the set pressure by the movement of the piston, the space above the piston is A passage is opened that communicates the piston chamber with the secondary pressure area, which is the lower space, and a valve seat is formed on the secondary pressure area side in the middle of the passage, and a spring biases the valve body that opens and closes the valve seat. A pressure reducing valve characterized in that it is biased and arranged.